Smoke generating tube

ABSTRACT

A SOLID ACID REAGENT AND A SOLID BASE REAGENT ARE SEPARATELY CONTAINED IN A BREAKABLE AMPOULE THAT IS ENCLOSED IN A PERFORATED ENVELOPE, WHICH IS IN TURN CONTAINED IN A PLIABLE TUBE. SMOKE IS GENERATED BY BREAKING THE AMPOULES AND PASSING AIR THROUGH THE TUBE.

P 25, 1972 P. w. MCCONNAUGHEY 3,658,719

SMOKE GENE-RATING TUBE Filed Oct. 9, 1969 j my NJ (l ke 7/ 1/ 1/ R m mmEC c WM W a United States Patent 3,658,719 SMOKE GENERATING TUBE Paul W.McConnaughey, Wilkinsburg, Pa., assignor to Mine Safety AppliancesCompany, Pittsburgh, Pa. Filed Oct. 9, 1969, Ser. No. 865,039 Int. Cl.B01d; B01f; B01j 13/00 US. Cl. 252-359 A 2 Claims ABSTRACT OF THEDISCLOSURE A solid acid reagent and a solid base reagent are separatelycontained in a breakable ampoule that is enclosed in a perforatedenvelope, which is in turn contained in a pliable tube. Smoke isgenerated by breaking the ampoules and passing air through the tube.

This invention relates to a smoke generating device and moreparticularly to a device in which a volatile acid and volatile base arereacted to produce a smoke of finely divided salt.

Compact, portable smoke generators are used for determining thedirection and velocity of air currents as, for example, in testingheating and air-conditioning installations. A cloud of smoke isgenerated, its direction and time of travel over a given distance areobserved. Conventional generators, commonly called ventilation smoketubes, operate by passing air through a bed of granular absorbentimpregnated with stannic chloride that reacts with moisture in the airto produce a dense smoke. The stannic chloride smoke, however, is acridand irritating.

It is an object of this invention to provide a ventilation smoke tube inwhich the smoke is generated by reaction of a volatile base and avolatile acid. Another ob ject is to provide such a tube in which theacid and base are segregated to provide a long storage life before useof the tube. Another object is to provide such a tube in which the acidand base are separated during use by a perforated barrier. Other objectswill be apparent from the following description and claims.

In accordance with this invention, a solid acid reagent and a solid basereagent are contained in separate sealed, breakable ampoules, and eachof the ampoules is enclosed in a perforated envelope. The solid reagentsconsist of a solid absorbent impregnated with a volatile acid or base.The envelopes are contained and spaced lengthise within a pliable tube.Means is provided to force atmosphere through the tube. When theampoules are broken, the perforated envelopes prevent intermixing of thesolid reagents while the volatile components of the reagents can diffusethrough the perforations in the envelope. When air is flowed through thetube, the volatile reagent components that have diffused outside theenvelope react to form a dense smoke that is discharged from the tube.

In the accompanying drawings:

FIG. 1 is a side view, partly in cross-section, of a smoke tube inaccordance with this invention, and

FIG. 2 is a perspective view of a perforated envelope in FIG. 1.

With reference to FIG. 1, solid reagent 2 is contained in a sealed glassampoule 4 which in turn is enclosed in a perforated envelope 6 ofpolyethylene tubing heat sealed at one end 8 and folded over at theother end 10. As best seen in FIG. 2, the envelope has a plurality ofperforations 12 made as by cutting slits in the tubing Wall. Theperforations provide only small dimension openings so that transfer ofthe volatile acid portion of the reagent is substantially by diffusion;that is, there is no significant convection flow of gases through theenvelope. A great variety of methods of making suitable perforations arewell known, such as, for example, slitting or puncturing with needles orelectrical sparks. Base reagent 14 is likewise contained in a breakableampoule 16 enclosed in perforated envelope 20. Both envelopes arecontained in a pliable tube 22 with suitable porous retainers such asglass wool plugs 24 and screens 26. Aspirator bulb 28 has conventionalcheck valves to permit purging of the atmosphere through the tube.

In operation, the pliable tube is squeezed to break ampoules 4 and 16,and aspirator bulb is squeezed to force air through tube 22. Thevolatile acid component from acid reagent 2 is carried on the air streamto contact the volatile base component from base reagent 14. Thevolatile components react to form a very finely divided coherent smokethat is discharged through porous retainers 24 and 26. No smoke isgenerated unless air is being flowed through the tube 22, and even afterbreaking the ampoules, the tube can be laid aside for one or two daysand still be operative.

The acids and bases are carried on an inert solid absorbent, such as,for example, paper, porous ceramics or glass, and granular inorganicabsorbents such as silica gel, alumina gel and pumice. Any liquidvolatile acid may be used, for example, aqueous nitric acid, preferredacids being aqueous hydrochloric acid and glacial acetic acid. Anyliquid volatile base may be used, for example, ammonium hydroxide, alkylamines such as isopropylamine, tert-butyl amine and cyclohexylamine andethylene diamine, and alkinolamines, such as monoethanolamine anddiethanolamine.

In one illustrative example of this invention, an acid reagent of 0.5cc. of anhydrous acetic acid on 1.0 cc. of 8-14 mesh silica gel wassealed in a glass ampoule and enclosed in a perforated envelope of0.002" polyethylene. The base reagent of 0.3 cc. ethylenediamine on 0.7cc. of 1020 mesh pumice was likewise sealed in a glass ampoule andperforated polyethylene envelope. The

reagent packages are enclosed in a 5-inch length of V8" ID. Tygon tubinghaving a Wire screen and Fiberglas plug adjacent each end. The tubing isconnected to the aspirator bulb so that air can be pumped over thereagents. The proportions of acid and base can be varied, to give asmoke that is acid, basic, or substantially neutral. In another example,the acid reagent is 0.6 cc. concentrated hydrochloric acid on 1.2 cc.silica gel and the base reagent is 0.6 cc. concentrated ammoniumhydroxide on 1.2 cc. pumice. Both tubes produced a dense coherent smoke.

I claim:

1. A smoke generating device for dispersing said smoke upon forcing airtherethrough comprising a first breakable ampoule, an acid reagentcontained in said ampoule consisting essentially of an inert solidabsorbent impregnated with a volatile acid reactant, a first flexibleperforated envelope enclosing said first ampoule and adapted to containthe acid reagent when the ampoule is broken, a second breakable ampoule,a base reagent contained in said second ampoule consisting essentiallyof a solid absorbent impregnated with a volatile base reactant reactivewith said acid reactant to form a smoke, a second flexible perforatedenvelope enclosing said second ampoule and adapted to contain saidsecond reagent when the ampoule is broken, said envelopes beingcontained and spaced lengthwise within a pliable conduit, whereby theampoules can be broken by squeezing the conduit.

2. A device according to claim 1 in which the said envelopes aresituated between porous plugs within said conduit.

References Cited UNITED STATES PATENTS 5/1947 Britt 252305 9/1964Searles 252305 X 5/1965 Zabriskie l6932 8/1965 Ruggiero 169-32 2/1935Houghton 21108 X 10 NORMAN YUDKOFF, Primary Examiner J. SOFER, AssistantExaminer US. Cl. X.R.

